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An unreachable block may have a route to a reachable block, don't fast-path…

Authored by nicholas on Apr 4 2019, 4:09 PM.

Description

An unreachable block may have a route to a reachable block, don't fast-path return that it can't.

A block reachable from the entry block can't have any route to a block that's not reachable from the entry block (if it did, that route would make it reachable from the entry block). That is the intended performance optimization for isPotentiallyReachable. For the case where we ask whether an unreachable from entry block has a route to a reachable from entry block, we can't conclude one way or the other. Fix a bug where we claimed there could be no such route.

The fix in rL357425 ironically reintroduced the very bug it was fixing but only when a DominatorTree is provided. This fixes the remaining bug.

llvm-svn: 357734

Details

Committed
nicholasApr 4 2019, 4:09 PM
Parents
rG875565e55931: [TextAPI] Prefix all architecture enums to fix the build on i386.
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